The present invention relates to method of and a device for optically counting small particles, like grains of seed and fertilizer and other materials employed in agriculture, in which the particles to be counted travel past a test field, interrupting as they do so a beam of light between a light emitter and a light detector. The invention also relates to a device for carrying out the process and having a light emitter on one side of the test field and a light receiver on the other side.
A method of this type is known, for example, from German Patent 2 534 130. Small particles, specifically seed that is being sown, is sent through a light barrier inside a test field. The light barrier generates a pulse every time its beam is interrupted. However, although the number of pulses does equal the number of particles passing through the light barrier under the assumption that they pass through individually and in order, when several particles pass through the test field essentially simultaneously, as may happen when the supply of particles to the test field cannot be controlled precisely enough for exactly one particle to enter the test field at a time, errors can occur due to the light barrier emitting only one pulse in this case as well.